Even if it probably isn’t exactly what you were looking for, I’d wholeheartedly recommend The Spy and the Traitor by Ben McIntyre, documenting the story of Oleg Gordievsky, the soviet spy that crossed over to the MI5 during the Cold War. It gave me a glimpse into the secret war at the time, the stuff that inspired James Bond, and the hardships and permanent threat faced by a spy trying to live several lives at once. It was one hell of a read.